Ignition system



Patented Oct. 17, 1933 IGNITION SYSTEM Herman C. Heaton, Chicago, lll.

Application July 31, issn. serial No. 472,019

i s claims. (ol. 11s-iss) My invention relates to ignition systems, particularly ignition systems for internal combustion engines and contemplates the provision with indicating means for such a system, particularly indicating means comprising one or a plurality of gas-filled tubes, of an improved pilot circuit connection therefor.

One advantage of my present invention is to eliminate the necessity for leading the high tension current to the indicating means. This enables disposition of the indicating means on the dash of an automobile, on the instrument board of an airplane or otherwise as and where desired, without extending the high tension current to such a position where the driver, pilot or other person is liable to come into contact with it.

Another advantage of my present invention is the provision of a pilot connection which will take off and supply but relatively slight current from the high tension leads to the indicating me or tubes.

As set out in my copending application, Serial No. 365,935, filed May 25, 1929, I have found that neon or 'other gas filled tubes are very sensitive and require but a very slight actuating electrical impulse. I further find that where a relatively great current exceeding that for lighting the tube or tubes at maximum brilliancy is employed relatively great differences or changes in the current will not show up in the tube unless the tube is so large as to be prohibitive for the intended purpose, but I nd that where relatively slight electrical impulses are employed to the tube or tubes the slightest differences in these impulses i5 will be accurately indicated by different degrees of illumination of a relatively small tube or a plurality of relatively small tubes suitable for the intended purpose.l

The pilot connection of the present invention by taking off and supplying but relatively slight electrical impulses from the high tension leads to the indicating tube or tubes provides therefor not only a more uniform or standardized action but an action whereby not only will the tube inthis is all done without drain upon the highA tension leads of the system.

According to the illustrated embodiment of my invention I employ electrostatically shielded dicate by lighting or ceasing to light but varia.-F tions in the ignition system will be accuratelyV cables i'n or as the high tension leads to theplugs and I obtain visual indications of the ignition characteristics through indications shown by one or more gas iilled tubes actuated by electrical impulses picked up from the high tension leads by the high tension cable shields and transmitted through pilot wires to the tube or tubes.

Where carried out in this manner not only are the advantages above set Aout obtained but a. grounding and shielding system is yprovided through the tube or tubes whereby the audibility of interference signals in radio receiving apparatus on airplanes, automobiles, motor boats or the like is reduced. l

Relatively sharp and standardized demarcations between the different degrees of illumination and the different indications conveyed thereby are contemplated. The indications may be used for indicating the condition of the respective spark plugs and the condition of the respective high tension circuit connections thereto or they may be used for indicating the resistance to passage of the ignition lspark across the spark gap or respective spark gaps as related to compression pressures in automotive engine cylinders or for indicating any other condition or conditions reected in the ignition characteristics of the engine.

Other features and advantages will appear from the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 is a schematic circuit diagram showing an embodiment of the invention;

Figure 2 is a fragmentary detail view partially 90 in section and showing one of the high tension shielded cable connections to one of the spark plugs Aand one manner of connecting therewith the pilot wire leading to the gas filled tube;

Figure 3 is a cross section through the high 95 tension shielded cable and showing the pilot wire connection of Figure 2;

Figure 4 is a fragmentary longitudinal section takenY on the line 4 4 of Figure 2 through one i y ofthe high tension shielded cable leads; and 'W0 Figure 5 is a more or less diagrammatic side elevational view of the gas tllled tube shown in Figure 1 While I shall describe the invention in connection with a multiple electrode gas filled tube this is for the purpose of 'illustration and it is to be understood that one or more tubes may be employed and that the details of the tube or tubes may vary.

In the diagram of Figure 1 a spark coil designated at 5 has a primary winding 6 intermittently connected to a source of low potential current by means of an interrupter 8 and a secondary winding 9 which forms a source of high potential ignithe ignition current by rotation around contacts 16 to which the spark plugs 10 are individually connected by the high tension leads 18.

The outer end of the arm 14 may contact directly with the contacts 16 successively inits rotation or it may, in conjunction with these contacts 16, close the respective circuits 18 through relatively small gaps to avoid unsatisfactory contact through carbonization or otherwise, after use. The distributor 12,.as well as the interrupter 8 may be operated from the timing gears of the engine in the usual or any preferred manner as well understood in the art. The circuit, as thus far described, is illustrated for the purpose of acquainting those skilled in the art with one embodiment of my present in'- vention. This circuit may be the circuit of any suitable or preferred ignition system and may vary. The impedances 20 and 21 correspond with the impedances 20 and 21 of Figure 1 of my copending application, Serial No. 365,934, filed May 25, 1929, and may be provided for plug and circuit testing purposes in accordance with the disclosure of that application. A suitable switch arm 22, pivoted at 23, is adapted for selectively completing either of the parallel or shunt paths through the impedances 20 or 21 to a ground connection 24.

According to my present invention I employ high tension insulated cables in or as the high tension leads 18 to theplugs 10. The particular cable shown in detail in Figures 3 and 4 comprises an inner conducting core 30, an electrostatic shield 31 surrounding the conducting core 30, insulation 32 interposed between the conductor 30 and the shield 31, and insulation 33 covering the shield 31. There is now on the market such a cable in which the conducting core 30 is of braided wire whereas the insulating winding 32 is of cotton thread or the like with an insulating sheath of rubber, rubber compound or the like interposed between the winding 32 andthe shield 31. The shield 31 is in the form of a metal braided Alayer and the insulating covering 33 is waterproof,

as for example of shellacked fabric.

The particular indicating means shown is in the form of a single gaseous or gas filled tube 35 common to all of the high tension leads 18 but it is to be understood that individual tubes may be employed in connection with the respective leads 18 and that therefore one or more gaseous tubes are contemplated within the scope of the present invention.

The particular tube 35 shown comprises a suitable bulb 36 having a base 37. The base 37 may be formed of insulating material or is at least formed toinsulate the terminals 38 from each other and from the terminal 39. It is preferably adapted for mounting in a support 40 and may have means such as slot and pin means 41 for retaining it in mounted position. The terminals 38 and 39 which extend through the base 37 are the terminals of electrodes 42 and 43 disposed `Within the bulb 36, the electrode 43comprising a disc-like electrode centrally disposed and the electrodes 42, there being one of these electrodes 42 for each high tension lead 18, surround the electrode 43 and are spaced equidistant circumferentially from each other and radially from the electrode 43. The electrode 43 is connected through a lead 45 to ground at 46. A rheostat 47 may be provided in the ground lead 45. As illustrative of an actual embodiment of the invention a 200,000 ohm rheostat is-contemplated at 47, the adjustable arm for adjusting the resistance to ground being indicated at 48.

The terminals of the electrodes 42 are connected to the respective high tension leads 18 by pilot wires 50, one of thepilot wires being connected to each terminal 42 at one end and at the opposite end each wire 50 has capacity connection with the lrespective cables 18 through the insulation thereof. Thesecapacity connections are, in the illustrated embodiment, obtained by terminal clips 52, oneon each of the Wires 50 and one clip is connected to the shield 31 of each of the respective cable leads 18 as for example in the manner shown in Figures 2 and 3, by removing a relatively small portion of the covering insulation 33`and clamping or attaching the clips 52 directly around and to the respective shields 31, although the particular details of the connection may vary.

By its capacity connection with the cable 18 through the shield 31 each pilot wire takes olf only relatively slight electrical impulses from-the cable and supplies same to the connected electrode of the tube, and with the ground connection at 46, each cable shield 31 is grounded through the gaseous tube means 35.

In operation as the spark impulses occur successively at the respective plugs 10 discharges occur successively across the gaps 56 between the respective electrodes 42 and the ground electrode 43. 'Ihe presence or absence of a discharge across any of the gaps 56 will indicate the presence or 1 gaps 56 indicating which plug or plug lead it is the condition of which is to be indicated.

Accordingly, I obtain visual indications of the ignition characteristics through indications shown by one or more gas lled tubes actuated byelec trical impulses picked up from the high tension leads by the high'tension cable shields and transmitted through pilot wires to the tube or tubes.

The indications may be used, as already pointed out, for indicating the condition of the respective spark plugs and the conditiono'f the vrespective high tension circuit connections thereto or they may be used for indicating thfe resistance to passage of the ignition spark across the spark gap or respective spark gaps as related to compression pressures in automotive engine cylinders or for indicating any other condition or conditions reflected in the ignition characteristics of the engine.

The capacity connections between the pilot wires 50 and the high tension leads are prefer- .ably disposed in close proximity to the respective plugs 10. It is believed that the vcapacity connections 52 will function better at the lower ends of the respective cables 18 adjacent to the respective plugs 10, as shown in Figure 1, by

avoiding the effect of leakage charges at or near the distributor head.

The particular gaseous tube shown is claimed broadly in my copending application, Serial No. 365,935, led May 25, 1929, and the specific form of this tube is claimed in its more limited aspects in my copending application, Serial No. 474,341 iiled August 11, 1930.

The system 'might be termed a phantom ignition system and the variable ground resistance serves as a means for adjusting its operation. I

have utilized a variable resistance in the ground.

circuit having a maximum value of 200,000 ohms. IV iind that this will tend to suppress stray currents which emanate from high potential leakage between the terminals of the distributor head. This may otherwise be a source of interference which interference is also increased by capacity effects between the individual conductors in the pilot Wire cable '70. Pilot wires shielded to overcome this eiect are therefore contemplated.

Provision may be made for shielding or partially shielding the tube means to promote visibility of the signals by eliminating the eect of -the daylight shining on the face of the instrument.

As has been pointed out in my previously filed copending applications, the lagging factor of a gaseous tube such as contemplated herein is negligible and this characteristic is admirably adapted for the present purposes. There is no afterglow, as compared with that in an incandescent filament lamp, and this is further important in providing a sharp demarcation between indications where the same tube is used for successively conveying different indications as successively the indications of the condition of the different spark plugs of a multi-plug engine, or successively the conditions of the circuit connections or ignition characteristics to the different plugs. I have referred to neon" tubes herein, but it is to be understood that I intend to include any equivalent gaseous tube regardless of the particular gas employed. For example, neon", argon and mercury vapor and argon and some other chemical in neon gas are now employed for obtaining different colored illuminations. Accurate indications of variations in the current flow through the tube ortubes are contemplated as already pointed out. In addition,

I contemplate mixing within the tube certain gases or substances each combination of which responds to certain intensities of current flow through them. This may be'employed to obtain or to augment the diierent indications for diffel-ences in current ow through the tube or tubes. I also contemplate carrying this matter of signal or indication intensity further within the tube as related to certain substances such as sodium .salts which I believe would be a distinct gain by adding to the visibility of the signals in daylight and by emphasizing distinctions ,in the signals or ind'cations obtained by differences in current flow through the tube or tubes.

With the particular tube means shown a rotary indicating effect is produced within the tube. It is conceivable that diilerent coloring of the indications might be employed for distinguishing the indications from each other.

One or more spark gap indicators may be emy ployed in place of the tube means 36 within the scope of my present invention. Where such an indicator is employed a suitable lens may be provided for optically magnifying the spark gap indications.

I further contemplate providing a shielded cable in or as the high tension lead from the coil 5 to the distributor 12 and connecting a neon or other gaseous tube with the shield of such a cable in the manner similar to the con-l nection of the wires to the shields of the cable leads 18. A gaseous tube so connected could be used as an indicator, marker or signal on an automobile, airplane or motor boat or it might be otherwise employed as suitable 0r desired.

I claim:

1. The combination with an ignition system comprising a'plurality of spark plugs, a plurality of high tension metallic shielded cable leads connected to said spark plugs, a source of current for said system and means for distributing the current to said plugs, of a plurality of pilot wires i connected to the cable shields, gaseous tube means connected to said pilot wires for indicating ignition characteristics and a ground connection for said gaseous tube means.

2. In an ignition system the combination of a high tension cable, spark plug means connected therewith, a metallic shield for said cable, means for visually indicating ignition characteristics, and a pilot wire transmitting electrical impulses picked up by said cable shield to said indicating means.

3. In an ignition system employing an electrostatic shielded cable extending to the spark plug, a ground connection for the electrostatic shield and means directly in said ground connection for giving a visual indication of the flow or absence of ow of ground current.

4. In an ignition system employing an electrostatic shielded cable extending to the spark plug, a ground connection for the electrostatic shield and a glow discharge .device in said ground connection for giving a visual indication of the ilow or absence of flow of ground current.

5. In 'an ignition system for an engine having 120 a plurality of spark plugs normally operating at the same voltage and wherein the respective spark plugs are connected to a source of high voltage by means of separate high voltage electric conductors prcvided with electrostatic shields, the combination with the shields of the respective conductors of a glow discharge device and connections between said device and the respective shields, said glow discharge device having a plurality of adjacent similar gaps between ground and the respective shield connections whereby under normal operation of the system all of the gaps glow with substantially the same intensity and a difference in glow indicates an abnormal condition of the associated spark plug circuit. il'

6. In combination with an explosive engine, a plurality of spark plugs, a distributor, a plurality of leads from said distributor to said spark plugs,

each lead being an insulated wire and having a metal sheath surrounding its insulation, a rela- I5) tively sensitive gaseous tube requiring a relatively slightly actuating electrical impulse connected to each sheath, and a ground connection for said gaseous tube.

HERMAN C. HEATON. I l.) 

